how to scale a signal to zero

[Kevin S - Engineer]

Hi,  I am trying to analyze a signal in LabVIEW.  The signal, however, has a voltage offset; so it hovers around 3 to 4 volts with the signal on top of that.  I am wondering if there is a way to scale to dc part of my signal to zero and look at only the ac part of it?  I know how I would do it with a circuit board but not LabVIEW, any help would be appreciated. 

Here is what I think the circuit would look like if that helps at all, it is a resistor in parellel with a capacitor: (R = resistor, C = Capcitor)

Vin----------C-------Vout

         |

        R

         |

   (Ground)

[johnsold]

Actually you would put the resistor to ground on the output side of the capacitor.

Use the Mean function form the Mathematics palette and subtract the mean from your data. The subtract function is polymorphic: you can put the array of data on one input and the mean (a scalar) on the other input. The output will be an array with the mean value subtracted from each element of the data.

Lynn

[smercurio_fc]

You can also use the AC & DC Estimator VI.




Message Edited by smercurio_fc on 06-17-2008 04:51 PM

[TroyK]

If the dc offset is constant and you're using a DAQmx device to acquire the signal, you can apply a custom scale to your signal as it comes in.

You can do that in MAX or as you create the task.

In MAX...


Or when creating the task...



Message Edited by Troy K on 06-18-2008 09:42 AM